Article pubs.acs.org/est
Isomer Profiles of Perfluoroalkyl Substances in Water and Soil Surrounding a Chinese Fluorochemical Manufacturing Park Hangbiao Jin,†,‡ Yifeng Zhang,†,‡ Lingyan Zhu,*,† and Jonathan W. Martin*,‡ †
Key Laboratory of Pollution Processes and Environmental Criteria, Ministry of Education, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin, P. R. China ‡ Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta AB T6G 2G3, Canada S Supporting Information *
ABSTRACT: Despite that China is the largest global manufacturer of perfluoroalkyl substances (PFASs), the manufacturing methods and isomer purity of these chemicals are generally unknown. Here, sampling was conducted around a major fluorochemical manufacturing park in China in 2012, including soil and water collection inside the park, including from a wastewater treatment plant (WWTP), as well as in surrounding rivers and soil (∼15 km radius). Perfluoroalkyl sulfonates (PFSAs) were lower than perfluoroalkyl carboxylates (PFCAs) in all samples, and short-chain (C4−C6) PFCAs were predominant. Perfluoroalkyl phosphonates and phosphate diesters were occasionally detected, but at low detection frequency. Branched isomers of perfluorobutanesulfonate (PFBS) are reported for the first time, accounting for 15−27% of total PFBS in water. An enrichment of isopropylPFOA (28%) was found in WWTP influent, suggesting its manufacturing primarily by isopropyl telomerization. More numerous branched isomers were observed for the longer C9−C13 PFCAs (e.g., C12 PFCA had 16 branched isomers), including high proportions of one major branched isomer (likely isopropyl), possibly as impurities from isopropyl-PFOA manufacturing. Overall, short-chain perfluorinated acids were the predominant PFASs being released, but PFOA was still a major chemical in use at this site, primarily from isopropyl telomerization.
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INTRODUCTION Perfluoroalkyl substances (PFASs) comprise a large group of chemicals that are characterized by a perfluorinated carbon chain attached to various functional groups.1 Among PFASs, perfluoroalkyl acids (PFAAs) have been manufactured for many commercial and industrial applications because of their chemical or thermal stability, and effective surfactant properties.2 Two main families of PFAAs, the perfluoroalkyl carboxylates (PFCAs) and perfluoroalkyl sulfonates (PFSAs), have received most scientific and chemical regulatory attention because they are environmentally persistent, globally pervasive,3,4 and long-chain PFCAs and PFSAs can bioaccumulate5 or may have adverse effects on humans and wildlife.6 PFCAs have been used for over 50 years as additives to facilitate polymerization in the production of fluoropolymers, mainly polytetrafluoroethylene and polyvinylidene fluoride.7 To date perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) are the predominant PFAAs detected in the global environment, including in seawater,8,9 indoor dust,10 background human samples,11 and even Arctic wildlife.12 The 3M Co., the major historic global producer, voluntarily phased out the production of PFOS, PFOA, and perfluorooctane sulfonyl fluoride (PFOSF; C8F17SO2F) in 2002, whereas in 2006, the U.S. EPA launched a global stewardship program to eliminate PFOA emissions.13 PFOS, its salts, and PFOSF derivatives are now listed in Annex B of the international Stockholm Convention, © 2015 American Chemical Society
and PFOA was recently nominated for consideration under the same framework. Since the phase out by the 3M Co., manufacturing of many PFASs has shifted to China to fulfill continuing demands. In 2006, more than 200 tons of PFOSF were produced in China, and China’s annual output increased rapidly from 2005 owing to domestic manufacturing restrictions in developed countries.14 Two primary industrial-scale processes have been used to synthesize PFAAs: electrochemical fluorination (ECF) and telomerization, and the use of these can be distinguished based on the isomer compositions and purity of the products. For example, historic ECF PFOA from 3M Co. had a consistent isomer composition of 78 ± 1.2% linear and 22 ± 1.2% various branched isomers, based on 18 production lots over 20 years.15 Telomerization yields relatively pure linear or isopropyl branched isomers.2 After the 3M Co. voluntarily phased out ECF perfluorooctyl chemistries in 2002, telomerization became the dominant manufacturing process in North America for PFCAs.16 As production shifted to China, little information on the extent of ECF versus telomerization PFAS manufacturing is known, albeit PFOA isomer profiles in four seawater samples collected in Received: Revised: Accepted: Published: 4946
January 13, 2015 March 16, 2015 March 23, 2015 March 23, 2015 DOI: 10.1021/acs.est.5b00212 Environ. Sci. Technol. 2015, 49, 4946−4954
Article
Environmental Science & Technology
Canada). HPLC-grade solvents, water, methanol, ammonium hydroxide (25% in water), and acetic acid (≥99%) were purchased from Fisher Scientific (Ottawa, ON, Canada). Sample Collection. The selected fluorochemical manufacturing park (FMP) is located along the Yangtze River in Changshu, Jiangsu Province, in eastern China. This park was founded in 1999 and has been in operation since then. Although no production numbers were available, this site may represent the largest fluorochemical manufacturing and application site in China. More than 15 domestic and overseas fluorochemical companies are located here, including Dupont, Solvay, Arkema, Kureha, and Daikin.29 Commercial fluoropolymer and fluorotelomer related products are among the major products manufactured by these factories. A total of 33 water and 28 soil samples were collected in or around the park in July 2012 (Figure 1). Briefly, 16 water samples were from the mainstream Yangtze River (W1−W5 and W23−W28) or two of its tributaries (i.e., W6−W7 and W29−W31 from Fushan and Wangyu River, respectively). Water samples were also taken from the wastewater treatment plant (WWTP) of the industrial park, including influent (W20), cyclic activated sludge technology (CAST) pool supernatant (W21), and WWTP effluent (W22). Well water (8.5−9.0 m underground) in Haiyu Town (W32), which is a small town ∼8 km from the FMP, was collected as a reference and for quality control. An additional 10 water samples (W8− W16 and W10B) and nine surface soil samples (S1−S9) were taken around various factories in the park. Another 16 surface soil samples were collected along the S338 Provincial road (S10− S19), and next to the Fushan River (S25−S27), and Wangyu River (S21−S23). Field blanks of laboratory water were also transported with the real samples during the sampling campaign. Water samples (98% ECF origin (likely a result of historical ECF manufacturing).17 Polyfluoroalkyl phosphate monoester (PAPs), polyfluoroalkyl phosphate mono- and diesters (diPAPs), perfluorophosphonates (PFPAs) and perfluorophosphinates (PFPiAs) are four classes of new PFASs with significant applications.18 PFPAs and PFPiAs are commercial surfactants manufactured for a range of consumer and industrial uses.19 High annual production volumes (10 000−500 000 lbs) of PFPAs and PFPiAs were reported between 1998 and 2002 in North America.20 MonoPAPs and diPAPs are used as grease and oil resistant agents for foodcontact paper, personal care products, household cleaning products and other applications, although some applications were banned by the U.S. EPA in 2008.21,22 Recently, high levels of diPAPs were reported with concentrations 14−74 times higher than median concentrations of PFOS, PFOA, and fluorotelomer alcohols (FTOHs) in indoor dust.23 Biotransformation of mono- and diPAPs to PFCAs was observed in Sprague−Dawley rats,24 indicating that exposure to these chemicals could be a significant contributor to PFCA body burdens in humans. To date there are few data on the manufacturing and application of these four new PFAS classes in China, thus investigations are warranted for assessing current environmental emissions. Total PFCA emissions to the environment are thought to be dominated by fluoropolymer manufacturing.7 In the current study, water and soil samples (including an industrial WWTP influent, activated sludge, and WWTP effluent) were taken around a fluoropolymer manufacturing industrial park in Jiangsu province, China. After WWTP treatment, wastewaters from factories in this park are released to the Yangtze River. An isomerspecific profiling technique was applied to assess the manufacturing origin (i.e., ECF versus telomerization) of monitored target compounds. The spatial distribution and transport of branched PFAA isomers were also investigated to better understand the variation of branched and linear PFAA concentrations with distance downstream on the Yangtze River. Although other studies of PFAS contamination or emissions from fluorochemical manufacturing facilities in China have been published,25−27 to our knowledge these are the first reported data on the isomer composition of PFAAs in the emissions or waste streams of any Chinese fluorochemical manufacturing facility.
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EXPERIMENTAL SECTION Nomenclature. The nomenclature system for PFCA and PFSA isomers was defined previously,28 but using PFOA as an example: linear PFOA was termed as n-PFOA, perfluoroisopropyl as iso-PFOA, 5-perfluoromethyl as 5m-PFOA, and total branched isomers as Br-PFOA. For remaining analytes, the potential branched isomers that could not be structurally assigned were labeled as BX (where x = 1, 2, 3, etc.) in order of decreasing retention time. The potential isomers were conservatively identified based on the following criteria: (i) peaks must be present in at least two different MS/MS transitions at the same retention time for C4−C7 PFCAs, and in three MS/MS transitions for long-chain PFCAs (C > 7), (ii) peaks must elute within a 4 min window before the respective linear peak for C4−C7 PFCAs, and within 7 min for long-chain PFCAs. Standards and Reagents. Details of all analytical standards used in this study are given in Table S1 in Supporting Information (SI). All native and 13C-labeled internal standards were purchased from Wellington Laboratories (Guelph, ON, 4947
DOI: 10.1021/acs.est.5b00212 Environ. Sci. Technol. 2015, 49, 4946−4954
Article
Environmental Science & Technology
Figure 1. (A) Sampling locations, flow direction, spatial distribution of PFCA concentrations, and (B) %iso-PFOA, %Br-PFOA, %iso-PFNA, and %BrPFNA in water samples (W1−W31) collected in and around the fluorine manufacturing park in Changshu, Jiangsu province of China. FMP means fluorine manufacturing park. WWTP means wastewater treatment plant. Note that W20, W21, and W22 are the WWTP influent, CAST pool water, and WWTP effluent, respectively.
using high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) with an Agilent 1100 Series liquid chromatography, or Waters ACQUITY ultra performance liquid chromatography (Waters, Milford, MA), coupled to a
Sciex API 4000 triple quadrupole mass spectrometer (Applied Biosystems-MDS Sciex, Concord, ON, Canada). Chromatographic separation of isomers was performed on an Ascentis Express F5 Column (2.7 μm, 90 Å, 10 cm × 2.1 mm, Sigma-Aldrich, 4948
DOI: 10.1021/acs.est.5b00212 Environ. Sci. Technol. 2015, 49, 4946−4954
Article
Environmental Science & Technology
(e.g., sample W10, W11, and W12). 6:2 diPAP was found in the upstream waters of the Yangtze River (W2) and in WWTP influent at concentration of 0.8 and 1.2 ng/L, respectively, which is ∼2 orders of magnitude higher than concentrations in Victoria Harbour, Hong Kong (
